¹³C-NMR dereplication of medicinal plant extracts using a home-made software

In natural products research, modern dereplication techniques reduce the usually time-consuming process of known compound isolation. Most commonly reported analytical tools during dereplication analysis are mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy [1]–[2]. Though low sensitive,¹³C-NMR has the advantage of being appropriate to (complex) mixtures whereas diastereomers can easily be discriminated. Since NMR spectrometers nowadays provide useful dataset in a reasonable time frame, we have embarked on writing a software dedicated to ¹³C-NMR dereplication. This (soon) freely available software, based on Python 3.5, processes ¹³C as well as DEPT 135 and 90 data, optionally allowing a carbon-type (i.e. CH₃, CH₂, CH and C) as well as a MW filtering. It requires predicted or experimental carbon chemical shifts δ(_C) databases (DB) [3] and displays interactive results that can be refined based on the user’s phytochemical knowledge [Fig. 1]

As a proof of concept, the present work presents the results obtained on two different medicinal plant extracts: Rosmarinus officinalis E392, used as an antioxidant food additive [4], and Mentha piperita essential oil, traditionally used in aromatherapy [5]. Here the predicted δ_C DB was built from 980 structures reported in Lamiaceae (SciFinder^®) using ACD/Labs^® software [6]. Interlocking ¹³C and DEPT information, our program managed to successfully identify all the major compounds in both extracts.

Fig. 1 General process of the dereplication program.

• References

• 1 Hubert J, Nuzillard JM, Purson S, Hamzaoui M, Borie N, Reynaud R. , et al. Identification of natural metabolites in mixtures: A pattern recognition strategy based on ¹³C NMR. Anal Chem 2014; 86: 2955-2962
• 2 Bakiri A, Hubert J, Reynaud R, Lanthony S, Harakat D, Renault JH. , et al. Computer-aided ¹³C NMR chemical profiling of crude extracts without fractionation. J Nat Prod 2017; 80: 1387-1396
• 3 Bruguière A, Derbré S, Coste C, Le Bot M, Siegler B, Leong ST. , et al. ¹³C-NMR dereplication of Garcinia extracts: predicted chemical shifts as reliable databases. Fitoterapia 2018; 131: 59-64
• 4 EFSA. Use orosemary extracts as food additive. EFSA journal 2008; 721: 1-29
• 5 EMA. Mentha piperitae aetheroleum. https://www.ema.europa.eu/en/medicines/herbal/menthae-piperitae-aetheroleum/ (Accessed May 2019 )
• 6 ACD/Labs. 2014 release